1. Field of the Invention
The present invention relates to a wireless network device and a method for reassociation between wireless networks using the wireless network device, and more particularly, to a wireless network device and a method for reassociation between wireless networks using the wireless network device designed to simplify a reassociation process of the device moving between the wireless networks.
2. Description of the Related Art
With the advancement in communication and network technologies, a wired network environment using wired media such as coaxial or optical cables is evolving into a wireless one using wireless signals in various frequency bands.
In line with the transition from wired to wireless technology, a computing device that contains a wireless interface module, enables mobility, and performs specific functions by processing various information (hereafter “a wireless network device”) is being developed and wireless technologies that enable effective communication between wireless devices on a wireless network are emerging.
There are two major architectures of wireless networks: infrastructure and ad-hoc networks.
As shown in FIG. 1, the infrastructure network contains an access point (AP) 110. On the other hand, as shown in FIG. 2, the ad-hoc network does not require an AP for communication.
In an infrastructure mode, an AP not only has connectivity to the wired network but also provides communication among wireless network devices within a wireless network. Thus, all data traffic in the infrastructure network is relayed through the AP.
In an ad-hoc mode, wireless network devices within a single wireless network can directly communicate with one another without using an AP.
Such wireless networks can be further classified into two types based on the presence of a coordinator.
In one type of network, which is called a “coordinator-based wireless network”, a randomly selected wireless device acts as a coordinator that allocates channel time to other wireless devices within the same wireless network for data transmission, and then the other wireless devices are allowed to transmit data only at the allocated time.
Unlike the coordinator-based wireless network, the other type of network allows all network devices to transmit data at any time desired without using a coordinator.
The coordinator-based wireless network is a single independent coordinator-centered network. When there are multiple coordinator-based wireless networks within a certain area, each network has a unique ID to distinguish itself from others.
Thus, while wireless devices can transmit data to and receive data from other network devices during channel time allocated by the coordinator on a coordinator-based network where they belong, they are not allowed to communicate with wireless devices belonging to another coordinator-based network.
For example, in a home network system containing two coordinator-based wireless networks, that is, first and second wireless networks 20 and 30, as shown in FIG. 3, it is assumed that the first wireless network 20 is provided in a living room and the second wireless network 30 is provided in a bedroom, respectively.
If a user desires to watch movies stored on a media server 31 in the living room using a portable moving picture player 21 in the living room, then the user cannot watch movies since there is no way to communicate between the first and second wireless networks 20 and 30. Thus, to watch the movies, the user has to go to the bedroom.
This problem may arise by restriction on range of radio waves, absence of information on another coordinator-based wireless network, and channel time allocation (CTA).
In addition, when the user moves from the living room to the bedroom to watch the movie, a portable moving picture player 21 attempts to reassociate with the second wireless network 30 after disassociating from the first wireless network 20. When the portable moving picture player 21 attempts to associate with the first wireless network 20, a coordinator of the second wireless network 30 allocates an identifier to the portable moving picture player 21 to distinguish it from other wireless network devices in the second wireless network 30.
Thus, there is an increasing demand for construction of a new network topology for data transmission and reception between wireless devices belonging to different coordinator-based wireless networks.
While an Institute of Electrical and Electronics Engineers (IEEE) 802.11x-based Wireless Local Area Network (WLAN) supports association/disassociation between wireless networks, a Wireless Personal Area Network (WPAN) such as IEEE 802.15.3, IEEE 802.15.1 or IEEE 802.15.4 WPAN provides a separate specification for association/disassociation between wireless networks. Thus, there is an urgent need to develop a method for association/disassociation between WPANs.
Korean Laid-open Patent Application No. 2004-0004726 proposes a method for reducing delay caused by frequent mobile host authentications in a WLAN environment using a reduced authentication token. However, the above-cited reference describes only a method for reducing authentication delay based on IEEE 802.11x. However, there has been no teaching nor suggestion based on IEEE 802.15.x.